Consequences Computations of LPG Pipeline Rupture. A. S. Yedigarov, Research Institute of Natural Gases & Gas Technology, 142717, Russia, Moskovskaya obl., Leninsky raion, p. Razvilka, VNIIGAS
Some results of the safety assessment of LPG main pipeline under design are presented. The study is devoted to computer simulations of liquefied petroleum gas (LPG) accidental releases, evaporation, vapour cloud propagation and dispersion for a number of different accident scenarios including hypothetical ones -- complete rupture of the main pipeline. As it is well known, the most dangerous accidents at LPG facilities are accompanied by the formation and evolution of the dense vapour clouds. The explosive or toxic cloud can travel over a long distance producing large hazardous zone and severe consequences. To solve this problem, the original three-dimensional hydrodynamic numerical model was used for the simulation of the turbulent flow and explosive vapour cloud evolution in the atmospheric boundary layer. The model is based on numerical integration of a complete set of unsteady non-linear Navier-Stokes equations of mass, momentum and energy balances within the scope of algebraic turbulent viscosity submodel. The following accident scenarios were examined: complete or partial rupture of the pipeline without pumping shut-down, stop pumping in a certain period of time (after leakage identification) and isolation of the pipeline damaged section by means of shut-off valves. Computations made it clear that the maximum hazardous zone and probable consequences depend to a great extent not only on the atmospheric stability conditions and wind speed but also on the time required for the accident identification and decision making. The performed numerical study also demonstrates the advantages and possibilities of mathematical modeling (accident imitations) in risk management issues for the correct reproduction of variable emergency situations on the LPG pipeline, elaboration of protective measures for consequences limitation and checking their efficiency.